More precisely, the invention relates to a device for checking curved tubes which enables a probe, such as an eddy-current probe, to be propelled pneumatically inside the tubes in order to check their condition. The fact is that the detection and localization of faults are essential checking operations in heat exchange apparatuses, more particularly when there is a risk that the two fluids will react with one another, as is the case in steam generators associated with liquid-metal-cooled nuclear reactors, in which the two fluids are respectively sodium and water. Faults liable to rupture a tube must therefore be detected as quickly as possible, so as to prevent them from getting worse and avoid the very serious consequences which might result both for the plant and the environment.
To this end a certain number of tube checking devices are already known. We may cite more particularly the device described in the article "Research and Development of the Method of Inserting Probe into Helically Coiled Tubes in Steam Generator for In-Service Inspection (ISI)" published in the Review IHI Engineering Review, vol. 13, No. 1 which enables a probe to be introduced pneumatically into a tube, by attaching the probe to a cable having floaters, the introduction of the cable into the tube being facilitated by a suitable guide mechanism which at the same time seals off the pneumatic propulsion system from the exterior.
French Pat. No. 2,320,542 of Aug. 7, 1975, in the name of the Commissariat a l'Energie Atomique discloses an eddy-current probe connected by a cable having suitable guide means, such as floaters, to the device enabling it to be introduced into the tube and extracted from the tube.
These prior art devices enable the probe to be introduced into a bent tube having small-radius bends and welding beads. However, they do not wholly satisfactorily solve the problem posed by the pneumatic introduction of the probe, which results in an excessive and highly irregular speed of probe movement, more particularly when a very long tube is being checked (for example, about 100 m). The speed of movement of the probe must therefore be reduced and regularized, so that it remains substantially constant from one end to the other of the tube to be checked.